Isolation and Histopathological Changes Associated with Non-Tuberculous Mycobacteria in Lymph Nodes Condemned at a Bovine Slaughterhouse.

Background: non-tuberculous mycobacteria (NTM) infect humans and animals and have a critical confounding effect on the diagnosis of bovine tuberculosis. The Official Mexican Standard (Norma Oficial Mexicana, NOM-ZOO-031-1995) for food safety regulates Mycobacterium bovis in cattle, but not the NTM species. The study's objective was to isolate and identify the NTM present in condemned bovine lymph nodes in a slaughterhouse, characterize the histological lesions, and correlate bacteriological and microscopic findings with the antemortem tuberculin skin test. Methods: from 528 cattle, one or two pooled samples of lymph nodes from each animal were cultured for Mycobacteria spp. and processed for histopathology. Results: mycobacteria were isolated from 54/528 (10.2%) of the condemned lymph nodes; 25/54 (46.2%) of these isolates were NTM; 4 bacteriological cultures with fungal contamination were discarded. Granulomatous and pyogranulomatous inflammation were present in 6/21 (28.6%) and 7/21 (33.3%) of the NTM-positive lymph nodes, respectively. The species of NTM associated with granulomatous lymphadenitis were M. scrofulaceum, M. triviale, M. terrae, and M. szulgai, while those causing pyogranulomatous lesions were M. szulgai, M. kansasii, M. phlei, and M. scrofulaceum. Conclusions: the NTM infections can cause false-positive results in the tuberculin test because of cross immune reactivity and interference with the postmortem identification of M. bovis in cattle.

Oral Vaccination With a Formulation Combining Rhipicephalus microplus Subolesin With Heat Inactivated Mycobacterium bovis Reduces Tick Infestations in Cattle.

Vaccines are an environmentally friendly alternative to acaracides for the control of tick infestations, to reduce the risk for tick-borne diseases affecting human and animal health worldwide, and to improve animal welfare and production. Subolesin (SUB, also known as 4D8) is the functional homolog of Akirin2 involved in the regulation of development and innate immune response, and a proven protective antigen for the control of ectoparasite infestations and pathogen infection. Oral vaccination combining protein antigens with immunostimulants has proven efficacy with increased host welfare and safety, but has not been used for the control of tick infestations. Here we describe the efficacy of oral vaccination with a formulation combining Rhipicephalus microplus SUB and heat inactivated Mycobacterium bovis (IV) on cattle tick infestations and fertility. The levels of IgG antibody titers against SUB and M. bovis P22, and the expression of selected immune response genes were determined and analyzed as possible correlates of protection. We demonstrated that oral immunization with the SUB+IV formulation resulted in 51% reduction in the number of female ticks and 30% reduction in fertility with an overall efficacy of 65% in the control of R. microplus infestations by considering the cumulative effect on reducing tick survival and fertility in cattle. The akr2, IL-1ß, and C3 mRNA levels together with antibody levels against SUB correlated with vaccine efficacy. The effect of the oral immunization with SUB+IV in cattle on tick survival and fertility is essential to reduce tick infestations, and extended previous results on the effect of R. microplus SUB for the control of cattle tick infestations. These results support the development of oral vaccines formulations for the control of tick infestations and the incidence of tick-borne diseases.

Seroprevalence of antibodies against Salmonella enterica subsp. enterica serovar gallinarum-pullorum in wild doves (Zenaida asiatica and Zenaida macroura) from the northeast of Mexico.

A cross-sectional survey was conducted in order to determine the seroprevalence and to identify some factors associated with the presence of antibodies against Salmonella enterica subsp. enterica serovar Gallinarum-Pullorum in white-winged (Zenaida asiatica) and mourning doves (Zenaida macroura) from hunting areas of Northeast Mexico. From September to October 2006, 201 serum samples were analyzed with the seroagglutination test. The overall seroprevalence of S. enterica subsp. enterica serovar Gallinarum-Pullorum was 26.3%, and was similar for white-winged doves (26.4%) and mourning doves (26.1%), but higher for juveniles (30.8%) and females (34.6%). Seroprevalence was associated with the weight of the doves (prevalence ratio [PR]=1.52, P<0.0001) and the municipality where the doves were hunted (PR=1.31, P<0.0001). This survey study emphasizes the need to conduct similar studies on wild birds to determine the risk of S. enterica subsp. enterica serovar Gallinarum-Pullorum to commercial flocks. In addition, to the best of our knowledge this is the first report of the serological evidence suggesting infection with S. enterica subsp. enterica serovar Gallinarum-Pullorum in wild white-winged and mourning doves.